U.S. patent application number 12/130828 was filed with the patent office on 2009-04-23 for system and method to manufacture an implantable electrode.
Invention is credited to Mayurachat Gulari, Jamille Farraye Hetke, Daryl R. Kipke, K. C. Kong, David S. Pellinen, Rio J. Vetter.
Application Number | 20090102068 12/130828 |
Document ID | / |
Family ID | 40562665 |
Filed Date | 2009-04-23 |
United States Patent
Application |
20090102068 |
Kind Code |
A1 |
Pellinen; David S. ; et
al. |
April 23, 2009 |
SYSTEM AND METHOD TO MANUFACTURE AN IMPLANTABLE ELECTRODE
Abstract
The method of the preferred embodiments includes the steps of
providing a base having a frame portion and a center portion;
building a preliminary structure coupled to the base; removing a
portion of the preliminary structure to define a series of devices
and a plurality of bridges; removing the center portion of the base
such that the frame portion defines an open region, wherein the
plurality of bridges suspend the series of devices in the open
region defined by the frame; and encapsulating the series of
devices. The method is preferably designed for the manufacture of
semiconductor devices, and more specifically for the manufacture of
encapsulated implantable electrodes. The method, however, may be
alternatively used in any suitable environment and for any suitable
reason.
Inventors: |
Pellinen; David S.; (Ann
Arbor, MI) ; Hetke; Jamille Farraye; (Brooklyn,
MI) ; Kipke; Daryl R.; (Dexter, MI) ; Kong; K.
C.; (Ann Arbor, MI) ; Vetter; Rio J.;
(Ypsilanti, MI) ; Gulari; Mayurachat;
(US) |
Correspondence
Address: |
SCHOX PLC
730 Florida Street #2
San Francisco
CA
94110
US
|
Family ID: |
40562665 |
Appl. No.: |
12/130828 |
Filed: |
May 30, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60980662 |
Oct 17, 2007 |
|
|
|
Current U.S.
Class: |
257/787 ;
257/E23.049; 438/124 |
Current CPC
Class: |
H01L 23/49541 20130101;
H01L 23/3185 20130101; H01L 21/561 20130101; H01L 2924/3025
20130101; H01L 2224/96 20130101; H01L 2924/0002 20130101; A61N 1/05
20130101; H01L 2224/04105 20130101; H01L 23/293 20130101; H01L
2924/0002 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
257/787 ;
438/124; 257/E23.049 |
International
Class: |
H01L 23/28 20060101
H01L023/28; H01L 21/00 20060101 H01L021/00 |
Claims
1. A method of building a series of encapsulated devices, the
method comprising the steps of: providing a base having a frame
portion and a center portion; building a preliminary structure
coupled to the base; removing a portion of the preliminary
structure to define a series of devices and a plurality of bridges,
wherein the series of devices are coupled to the center portion of
the base, and wherein the plurality of bridges are coupled to the
frame portion of the base and to the series of devices; removing
the center portion of the base such that the frame portion defines
an open region, wherein the plurality of bridges suspend the series
of devices in the open region defined by the frame; and
encapsulating the series of devices.
2. The method of claim 1 wherein the step of providing a base
having a frame portion and a center portion includes the step of
providing a silicon wafer.
3. The method of claim 1 wherein the step of providing a base
having a frame portion and a center portion includes the step of
removing a portion of the base such that the base defines a trench
that separates the center portion of the base from the frame
portion of the base.
4. The method of claim 3 wherein the step of removing a portion of
the base such that the base defines a trench that separates the
center portion of the base from the frame portion of the base is
performed through a deep reactive ion etching (DRIE) process.
5. The method of claim 1 wherein the step of building a preliminary
structure coupled to the base includes the step of building a
plurality of layers coupled to the base.
6. The method of claim 5 wherein the step of building a plurality
of layers coupled to the base includes the step of building a
plurality of layers of material chosen from the group consisting of
silicon, metal, polymer, and any combination thereof.
7. The method of claim 5 wherein the step of building a plurality
of layers coupled to the base further includes the step of building
an electrode site and a conductive lead.
8. The method of claim 7 further comprising the step of removing a
portion of the encapsulation from the series of devices to expose
the electrode site.
9. The method of claim 8 further comprising the step of
electroplating the exposed electrode site.
10. The method of claim 1 wherein the step of removing a portion of
the preliminary structure to define a series of devices and a
plurality of bridges is performed through a reactive ion etching
(RIE) process.
11. The method of claim 1 wherein the step of removing the center
portion of the base such that the frame portion defines an open
region includes the steps of creating a mask on the base and
patterning the mask to expose the frame portion of the base.
12. The method of claim 11 wherein the step of removing the center
portion of the base such that the frame portion defines an open
region further includes the step of modifying the frame portion of
the base such that it behaves as an etch stop.
13. The method of claim 12 wherein the step of modifying the frame
portion of the base is performed through deep boron diffusion.
14. The method of claim 12 wherein the step of removing the center
portion of the base such that the frame portion defines an open
region is performed with a wet etchant that removes the unmodified
portions of the base.
15. The method of claim 1 wherein the step of encapsulating the
series of devices includes the step of encapsulating the series of
devices, the plurality of bridges, and the frame portion of the
base in a conformal coat of a coating.
16. The method of claim 1 further comprising the step of uncoupling
the series of devices from the plurality of bridges and from the
frame portion of the base.
17. A method of encapsulating a semiconductor device, the method
comprising the steps of: providing a wafer that defines an open
region; building a semiconductor device; building a plurality of
bridges coupled to the wafer and coupled to the semiconductor
device such that the plurality of bridges suspend the semiconductor
device in the open region defined by the wafer; and encapsulating
the semiconductor device.
18. The method of claim 17 wherein the step of providing a wafer
that defines an open region includes the steps of: providing a
wafer having a frame portion and a center portion; modifying the
frame portion of the wafer such that it behaves as an etch stop;
and removing the center portion of the wafer such that the frame
portion defines an open region.
19. The method of claim 17 wherein the steps of building a
semiconductor device and building a plurality of bridges coupled to
the wafer and coupled to the semiconductor device include the steps
of: building a preliminary structure coupled to the wafer; and
removing a portion of the preliminary structure to define a
semiconductor device and a plurality of bridges.
20. The method of claim 19 wherein the step of building a
preliminary structure coupled to the wafer includes the steps of:
building a plurality of layers coupled to the wafer; and building
an electrode site and a conductive lead.
21. The method of claim 17 wherein the step of encapsulating the
semiconductor device includes the step of encapsulating the
semiconductor device, the plurality of bridges, and the wafer in a
conformal coat of a coating.
22. The method of claim 17 further comprising the step of
uncoupling the semiconductor device from the plurality of bridges
and from the wafer.
23. A semiconductor device encapsulation system, comprising: a
wafer that defines an open region; a plurality of bridges coupled
to the wafer that extend from the wafer into the open region; and a
semiconductor device coupled to the plurality of bridges such that
the semiconductor device is suspended in the open region.
24. The semiconductor device encapsulation system of claim 23
further comprising a coating that encapsulates the semiconductor
device.
25. The semiconductor device encapsulation system of claim 24
wherein the semiconductor device is removable from the plurality of
bridges such that upon removal, the semiconductor device is
encapsulated in a conformal coat of the coating.
26. The semiconductor device encapsulation system of claim 23
wherein the wafer is made of silicon.
27. The semiconductor device encapsulation system of claim 23
wherein the semiconductor device and the plurality of bridges
include a same plurality of layers.
28. The semiconductor device encapsulation system of claim 27
wherein the material of each layer is chosen from the group
consisting of silicon, metal, and polymer.
29. The semiconductor device encapsulation system of claim 27
wherein the semiconductor device further includes an electrode site
and a conductive lead.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/980,662, filed 17 Oct. 2007 and entitled "Method
to Manufacture an Implantable Electrode", which is incorporated in
its entirety by this reference.
TECHNICAL FIELD
[0002] This invention relates generally to the implantable
electrodes field, and more specifically to an improved method to
manufacture encapsulated implantable electrodes.
BACKGROUND
[0003] Conventional implantable electrodes are coated with
dielectrics to provide increased protection from moisture
absorption. The majority of encapsulation methods for
microfabricated electrodes are completed at the device level,
rather than the wafer level, and therefore are more labor intensive
and preclude further batch processing of the electrodes. For
example, when the devices are encapsulated at the device level,
electrode sites must be exposed individually on each device,
typically with laser ablation. Alternatively, while some methods do
include coating the devices at the wafer level, they involve a
layering or "sandwiching" technique that allows for potential fluid
leakage between layers. Thus, there is a need for an improved
method to manufacture an implantable electrode. This invention
provides such an improved and useful method.
BRIEF DESCRIPTION OF THE FIGURES
[0004] FIG. 1 is a schematic drawing of the method shown as a
series of side views of a portion of the wafer.
[0005] FIG. 2 is a schematic drawing of the method shown as a
series of top views of a portion of the wafer.
[0006] FIGS. 4 and 5 are schematic drawings of a cross section view
of a final electrode.
[0007] FIG. 6 is a schematic drawing of the method shown as a
series of both top views (LEFT) side views (RIGHT) of a portion of
the wafer.
[0008] FIGS. 7A, 7B, and 7C, are drawings of the device
encapsulation system of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0009] The following description of preferred embodiments of the
invention is not intended to limit the invention to these
embodiments, but rather to enable any person skilled in the art to
make and use this invention.
[0010] As shown in FIG. 6, the method of the preferred embodiments
includes the steps of providing a base having a frame portion and a
center portion S200; building a preliminary structure coupled to
the base S112; removing a portion of the preliminary structure to
define a series of devices and a plurality of bridges, wherein the
series of devices are coupled to the center portion of the base,
and wherein the plurality of bridges are coupled to the frame
portion of the base and to the series of devices S114; removing the
center portion of the base such that the frame portion defines an
open region, wherein the plurality of bridges suspend the series of
devices in the open region defined by the frame S202; and
encapsulating the series of devices S204. The method is preferably
designed for the manufacture of semiconductor devices, and more
specifically for the manufacture of encapsulated implantable
electrodes. The method, however, may be alternatively used in any
suitable environment and for any suitable reason.
[0011] As shown in FIGS. 1-3, step S200, which recites providing a
base having a frame portion and a center portion, includes the
steps of providing a wafer S102 and removing a portion of the wafer
to define a frame S104. Step S202, which recites removing the
center portion of the base such that the frame portion defines an
open region, includes the steps of creating a mask on the wafer
S106; patterning the mask to expose the frame S108; and modifying
the frame and removing the remainder of the mask Silo; and removing
unmodified wafer material S116. Step S204, which recites
encapsulating the series of devices, includes the step of
encapsulating the devices, the bridges, and the frame S118. The
method further includes the steps of removing material to expose
sites on the devices S120 and removing the series of devices from
the bridges and the frame S122.
[0012] Step S102, which recites providing a wafer, functions to
provide a wafer 10 upon which to build the series of devices 16.
The wafer 10 is preferably a standard wafer conventionally used in
semiconductor device fabrication, but may alternatively be any
suitable wafer. The wafer 10 is preferably made from silicon, but
may alternatively be made from gallium arsenide, indium phosphide,
or any other suitable material.
[0013] Step S104, which recites removing a portion of the wafer to
define a frame, functions to remove a portion of the wafer 10, such
that the wafer 10 defines a trench that separates the center wafer
portion from the outer frame portion 12 of the wafer 10, as shown
in FIG. 1. This step is preferably performed through a deep
reactive ion etching (DRIE), but may alternatively be performed
through any other suitable removal process, such as other dry
etching methods, wet etching, chemical-mechanical planarization,
laser etching, or any combination thereof. As shown in step S104 of
FIG. 3, multiple portions are preferably removed at the wafer level
to define a series of trenches that separate a series of center
wafer portions from a series of outer frame portions.
[0014] Step S106, which recites creating a mask on the wafer,
functions to cover the center wafer portion, the trench, and the
outer frame portion 12 in a mask, as shown in step S106 of FIG. 1.
The portions of the wafer with the mask will resist modification at
later stages of the process, while the unmasked portions are
susceptible to modification. The mask is preferably created through
oxidation, but may alternatively be created through any suitable
process.
[0015] Step S108, which recites patterning the mask to expose the
frame, functions to remove a portion of the mask to expose a
portion of the wafer 10. As shown in step S108 of FIG. 1, the mask
is preferably removed from the outer frame portion 12 and remains
on the center wafer portion.
[0016] Step S110, which recites modifying the frame and removing
the remainder of the mask, functions to modify the portions of the
wafer where the mask was removed (the masked portions of the wafer
remain unmodified) and then to remove all remaining portions of the
mask. The modification is preferably deep boron diffusion, but may
alternatively be any suitable modification to the unmasked wafer
portions. The modification preferably alters the wafer such that
the modified portion will behave as an etch stop during later
stages of the process. As shown in step Silo of FIG. 1, the outer
frame portion is modified while the center wafer portion preferably
remains unmodified. As shown in step Silo of FIG. 3, the series of
outer frame portions are modified, while the series of center wafer
portions preferably remain unmodified. Once the modification is
complete, the remainder of the mask is stripped away.
[0017] Step S112, which recites building a preliminary structure
coupled to the base, functions to build the preliminary structure
14 on the wafer. As shown in step S112 of FIG. 2, at least one
preliminary structure 14 is built over the center wafer portion and
the outer frame portion. The preliminary structure 14 is preferably
one of several variations.
[0018] In a first variation, as shown in FIGS. 1-4, the preliminary
structure 14 is an electrode structure that includes conductive
leads that transfer signals between the electrode sites and the
bond pads. The conductive leads are preferably polysilicon or
metal, but may alternatively be made out of any suitable material.
The first dielectric is preferably an inorganic stack of silicon
dioxide, silicon nitride, and silicon dioxide (preferably a
tri-layer stack of inorganic dielectrics). The first dielectric
stack provides electrical insulation to the underlying conductive
leads. Alternatives to the first dielectric include silicon carbide
and even other polymers such as polyimide or parylene. The second
dielectric may be the same as the first dielectric stack, or may
alternatively be a vapor deposited polymer such as parylene, PTFE,
other fluoropolymers, silicone, or any other suitable material. The
second dielectric provides additional electrical insulation to
leads. The electrode structure preferably also includes a site 20.
The site 20 is preferably an electrode site such as a recording
and/or stimulation site. The site 20 is preferably made from gold,
iridium, or platinum, but may alternatively be made from any
suitable material. The sites 20 may further include bond pads that
provide a point of contact to an external connector. The bond pads
are preferably gold, but may alternatively be any suitable
material. The preliminary structure 14 in this variation may
further include a metal shield that provides extra electrical
isolation of the leads from the surrounding environment. The metal
shield is preferably titanium, but may alternatively be any
suitable material.
[0019] In a second variation, as shown in FIG. 5, the preliminary
structure 14 is an electrode structure, which includes a center
layer that is preferably metal conductors and sites 20. The metal
is preferably platinum, but may alternatively be any other suitable
material. The center layer is preferably sandwiched between layers
of polyimide. The outer material may alternatively be any other
suitable material.
[0020] Although the preliminary structure 14 is preferably one of
these variations, the preliminary structure 14 may be any suitable
device fabricated through any suitable method. The preliminary
structure 14 may further be a microfluidic device, a MEMS sensor, a
MEMS actuator, or any other suitable wafer level batch fabricated
device.
[0021] Step S114, which recites removing a portion of the
preliminary structure to define a series of devices and a plurality
of bridges, functions to remove portions of the preliminary
structure 14 such that the remaining portions of the preliminary
structure define a series of devices 16 and a series of bridges 18.
As shown in step S114 of FIG. 1, a removal process is performed to
delineate a series of devices 16 and a series of bridges 18. As
shown in FIG. 2, the devices 16 are located generally over the
center wafer portion 10' and the bridges 18 function to secure the
devices 16 to the outer frame portion. As shown in step S114 of
FIG. 3, the series of devices 16 are located generally over the
series of center wafer portions and the series of bridges 18
function to secure the devices 16 to the series of outer frame
portions. This step is preferably performed through a reactive ion
etching (RIE), but may alternatively be performed through any other
suitable removal process, such as other dry etching methods, wet
etching, chemical-mechanical planarization, laser etching, or any
combination thereof.
[0022] Step S116, which recites removing unmodified wafer material,
functions to remove the unmodified center wafer portion 10' beneath
the series of devices 16, while the outer frame portion 12 that was
modified in step Silo remains, as shown in step S116 of FIG. 1. The
outer frame portion 12 supports the devices 16 suspended by the
bridges 18, as shown in FIG. 2. As shown in step S116 of FIG. 3,
the series of bridges 18 function to secure the series of devices
16 to the series of outer frame portions 12. This step is
preferably a silicon dissolution that removes the unmodified (non
boron doped) portions of silicon from the wafer. The removal
process is preferably formed with wet etchants for silicon. These
etchants may include potassium hydroxide (KOH), Tetramethylammonium
hydroxide (TMAH), and any other suitable etchant that functions to
remove silicon from the wafer.
[0023] Step S118, which recites encapsulating the electrodes, the
bridges, and the frame, functions to encapsulate the remaining
portions of the structure in a conformal coat. The coating material
is preferably a polymer such as parylene, but may alternatively be
any suitable material. In this step, the bridges 18 secure the
devices 16 in place while the devices 16 are fully encapsulated in
the polymer. As shown in step S118 of FIGS. 1-3, the devices 16,
the bridges 18, and the outer frame portions 12 are all
encapsulated with the coating material.
[0024] Step S120, which recites removing material to expose sites
on the electrodes, functions to remove the polymer coating from
specific regions on the devices 16 such that the sites 20 are
exposed, as shown in step S120 in FIGS. 1-3. The sites 20 are
preferably exposed using photo-lithography such as a combination of
wet and dry etching, but may alternatively be exposed through any
other suitable method such as through use of a laser. The exposed
sites 20 may further be electro-plated or any other suitable
post-encapsulation steps. In this step, the bridges 18 secure the
devices 16 in place while the devices 16 undergo any suitable
post-encapsulation steps.
[0025] Step S122, which recites removing the series of electrodes
from the bridges and the frame, functions to remove the completed
devices 16 from the frames 12. The bridges 18 are preferably cut or
removed in any suitable fashion such that each device 16 is a
separate device, as shown in step S122 of FIGS. 1 and 2. As shown
in FIG. 3, the series of outer frame portions 12 remain once the
devices 16 are removed.
[0026] The elements of this process may be grouped into microscale
elements and macroscale elements. The microscale elements are those
that make up the preliminary structure 14 such as the sites 20 (the
electrode sites and the bond pads) and the conductive leads.
Macroscale elements are those that provide structural support to
the device during the steps of the manufacturing method,
specifically during the encapsulation and post-encapsulation steps.
The macroscale elements include the outer frame portion 12, which
allows for suspension of the devices 16 and the bridges 18 which
hold the devices 16 within the frame 12 and to each other.
[0027] As shown in FIG. 7A, the semiconductor device encapsulation
system 300 of the preferred embodiments includes a wafer 302 that
defines an open region 304, a plurality of bridges 306 coupled to
the wafer 302 that extend from the wafer 302 into the open region
304, and a semiconductor device 308 coupled to the plurality of
bridges 306 such that the semiconductor device 308 is suspended in
the open region 304. The semiconductor device encapsulation system
300 is preferably designed for the manufacture of semiconductor
devices, and more specifically for the manufacture of encapsulated
implantable electrodes. The semiconductor device encapsulation
system 300, however, may be alternatively used in any suitable
environment and for any suitable reason. As shown in FIG. 7B, the
semiconductor device encapsulation system 300 further includes a
coating 310 that encapsulates the semiconductor device. As shown in
FIG. 7C, the semiconductor device 308 is removable from the
plurality of bridges such that upon removal, the semiconductor
device is encapsulated in a conformal coat of the coating 310.
[0028] Although omitted for conciseness, the preferred embodiments
include every combination and permutation of the various steps,
wafers 10, frames 12, preliminary structures 14, devices 16,
bridges 18, sites 20, microscale elements and macroscale elements.
Furthermore, any suitable number of preliminary structures and/or
devices may be fabricated together. For example, the fabrication
may be accomplished via batch processing, preferably on an
automated probe station equipped with a laser, but may
alternatively be completed with any other suitable equipment.
[0029] As a person skilled in the art will recognize from the
previous detailed description and from the figures and claims,
modifications and changes can be made to the preferred embodiments
of the invention without departing from the scope of this invention
defined in the following claims.
* * * * *